Continuous titration apparatus



y 22, 1952 E. E. MORSE 2,604,383

CONTINUOUS TITRATION APPARATUS Filed March 16, I946 INVENTOR. ER W//\/E. MORSE Patented July 22, 1952 UNITED STATES PATENT OFFICE CONTINUOUSTI'TRATIO'N APPARATUS Erwin E. Morse, wooalanaloauf. ApplicationMarchic, 1946', Serial No. 654,927

'12 Claims. 1 The invention relates to apparatus for performing'continuous titration.

- One" of the most important processes in thefield of chemistry is thatof titration.- In thisproce'ss, the concentration of a dissolvedsubstance in solution is deter-tinned by measuring the smallest amountof it required to bring about a given effect in reaction with anothersolution or substance In performing any titration,the chemist must havesome means of deter-miningthe point of equivalence of the two reaoti'ngchemicals. In certain cases where one of the reactants serves as its ownindicator, this can be seen by a sudden change in the color of thereacting solutions. In other cases, completionof titration is indicatedby a change in the color of a third substance.

since the processof titration isachemic'al one, with associated changesin physico chemi'cal properties of the solution, the variation in themagnitude of these properties can often be used as an indirect indicatoroi the completeness of titration. An important type of: indirectindicater which functions by means of achange in a physico-ch'emicalproperty of the solution is the galvanic cell, which produces a smallbut definite electromotive force, the value of which depends o thechemical state or the solution. The choice" of electrodes for thegalvanic cell is determined by the particular titration reaction undercon s'ider'atiom In my present'invention I make use of a galvanic cell,activated by the solution under examination, to initiate the operationand control of devices for carrying on continuously and automatically,and recording; a titration process of special usefulness in themanufacture of beet sugar.

it is therefore'a broad object or my inventionto provide. an apparatusand process for perform ing an automatic and continuous titration of anacid solution with an alkaline solution; or of an alkaline solution withan acid solution. It is also an object of my invention in a narrowersense to provide ameans for and i'nethod' of automatically andcontinuously eontrqmng, m asuring and re cording the alkalinity of thefirst carbonation fil= trate in the manufacture of beet sugar. I

invention p'os'sesses other va1uab1'e;reatures, some of which" with theforegoing will be set forth at length in the following description wherethat form of the invention which has been selected for illustration inthe drawings accompanying and forming a part of the presentspeciflcation is explained. In said drawings, one form of the inventionis shown. but it is to be understood that it is not limited to thatform, since the invention as set forth in the claims may bee'inbodied'in a plurality or forms.

In the drawings, the figure is a diagrammatical view of the entireapparatus of my inventiom While it will be obvious that my inventionmaybe adapted and applied in many different manufacturing and productionarts, its application in the making of beet sugar will be treated in thefollowing explanation of my invention.-

In the production of sucrose from sugar beets,- one of themost-important steps inthe process is the defecation of diffusion juicewith mill; of lime and carbon dioxide. The first part ofthe' defecationprocess is termed first carbonation." The mixture obtained from themixing of di'fi u sicnjuice, milk of lime oi sac'charate milk, andcarbon dioxide is called first carbonation juice. Probably the mostimportant controlling variable in the first carbonation process is thealkalinity of the filtered juice;

The determination of alkalinity is simply a titration of an alkalinesolution with an midsumtion. The filtered first carbonation" juice isthe alkaline solution; and 0.0357 normal sulfuric acid filtered juice istaken, the volume of a'cidre quired for neutralization, divided by 100,isthe numerical measure of the alkalinity. Further more, the alkalinityequals the number of grams of calcium oxide per milliliters ofjuice,.assuming that calcium hydroxide is the only alkaliv present inthe juice.

First carbonation control depends primarily uponthe determination of thealkalinity which is made manually by the carbonation operator. Thus theoperator takes a sample of firstcarbonation juice from the carbonationtanks, filters the juice and titrates a 10 milliliter sample of thefiltrate with 00357 normal sulfuric acid, using 'phenol-phthaleinas acolor indicator. If the measured alkalinity. of the juice varies fromthe desiredfigure. the addition otthe milk of lime or carbon dioxide gasis changed so as to obtain the desired figure.

Approximate alkalinity control is frequently obtained by the use ofintermediary devices such as pH or conductivity controllers. Theprincipal objection to these devices is that other factors such astemperature or percentage of lime may alter the relationship betweenalkalinity and pI-l or alkalinity and conductivity;

Referring to the drawing, a continuous flow of first carbonation jiiicepasses through sample line 2, into the filtf pm; 3, then bill; theoverflow pipe 4 and back to the process. If the Dorr system ofcontinuous first carbonation is used, it is convenient to connect sampleline 2 to the pressure side of the recirculation pump. With othercarbonation systems, the sample line should be so installed that thesample is representative of the completely limed and carbonated juice. Afilter 6 consisting of a perforated cylindrical frame covered with afilter medium such as 16- ounce duck filter cloth is immersed in thejuice, and connected by pipe 1 to a filtrate receiver 8. A filtrationarea of 25 square inches is usually satisfactory under normal operatingconditions.

The filtrate receiver 8 is also connected through the pipes 9 and I0,between which a trap I2 is interposed, and through the three-wayreciprocating valve l3, alternately with a pressure tank l4 and a vacuumtank IS. The trap protects the valve from the juice in the vacuum phaseof its operation; and provides a convenient place for mounting a gaugeH, on which the degree of vacuum and the amount of pressure in theconnecting lines may be indicated. The trap is also provided with adrain valve l8 at its lower coned end. v

The vacuum may be conveniently set at 3 inches of mercury for 17 secondsand the pressure at 1 lb. per sq. in. for 7 seconds. The filtered juicecollects in the filtrate receiver 8, while the vacuum is being appliedto the system and is blown into the supply tank l9 through theconnecting pipe 2|, when pressure is applied to the filter.Simultaneously the layer of solid matter which collects on the filtersurface during the vacuum part of the filtration cycle is blown off.Admission of air to the filtrate receiver 8 is prevented during thevacuum part of the cycle by the check valve 22, interposed in the pipe2|.

The supply tank I9 is provided with an overflow pipe 23, to a wastereturn line; and the tank is advantageously madeof such a size that theretention time of the juice in the tank is short. A volume of 135milliliters below the overflow level is a satisfactory value for firstcarbonation juice.

Connected to the bottom of the supply tank l9 bya pipe 24, controlled bya valve 25, are the coils 26 of a heat exchanger 21, to which a coolingmedium is supplied through the pipe 28. Again, it is advantageous toconstruct the heat exchanger so that the minimum volume of .juicecommensurate with adequate cooling is' present in the cooling coil atany time. 8 ft. of A" outside diameter copper tubing is satisfactory forfirst carbonation juice if the cooling medium is water at 20 C.

The filtrate fiows at a steady rate through the valve adjusted passageof the pipe 24, and into the heat exchanger, from which the cooledflltrate flows through the pipe 29 to the constant level tank 3|,provided with an overflow pipe 32 to the waste return line. The tank ismounted for vertical adjustment so that the head of filtrate dischargingfrom the bottom thereof through the flexible conduit 33 may be varied.The discharge conduit 33 terminates in a restricted orifice convenientlyprovided by a piece of capillary glass tubing 34, in adjustably fixedposition and having an internal diameter of .044" and a length of 1".

The constant level tank should be quite small so that the retention timeof the juice flowing through it is reduced to a negligible amount. Avolume of 20 milliliters or less above the outlet to 4 the dischargetube 33, and below the overflow level, is satisfactory for firstcarbonation juice.

The flow of cooled, filtered juice to the constant level tank 3| isconveniently set at about milliliters per minute by adjustment of thefiltrate throttling valve 25. The juice flows through conduit 33 and isdelivered from the restricted orifice of the tube 34, held by anysuitable means in a fixed position. The rate of fiow of the liquid isdetermined by the dimensions of the capillary tip and the static head ofthe liquid column above this orifice, it being assumed that thetemperature of the liquid remains constant. By varying this static head,the rate of flow may be set at any desired value. A convenient rate offlow with first carbonation filtrate is 75.0 milliliters per minute.

In some titrations there may be no need to filter and cool the materialto be analyzed. In that case, the sample to be tested will runcontinuously from the sample line 2, through the pipe 36, indicated indashed lines, into the constant level tank 3|. If the material is hot orif it has a varying temperature, the sample may be admitted through pipe31 into pipe 24, above valve 25. The automatic titration may beconducted at any of many different temperatures. The range of 20-25 C.is convenient for most titrations.

Means are provided for supplying a flow of acid solution and mixing itwith the flow of juice, automatically controlling the amount of acid bymeans responsive to the galvanic current generatedby the mixturefunctioning as an electrolyte in a galvanic couple. A pair of acid tanks4| and 42 are connected through the three-way valve-43 and pipe 44 todischarge into the con stant level tank 46. Constant level is maintainedby means of a glass float valve 4'1. The use of either of two tanks,makes continuous operation possible since acid may be withdrawn from onewhile the other is replenished.

From the constant level tank 46, the acid flows through the conduit 48to the inner end of a dispensing tube 49, to which it is flexiblyconnected, and which is mounted for movement like the hand of a clock onthe pivot shaft 5|. The tube is provided with a capillary tip 52 and mayhave an internal diameter of .044" and be 1.13" long. The acid flowsthrough the dispensing tube by gravity to drop from the capillary tipinto an arcuate trough 53, fixed below the capillary tip throughout itsrange of movement in the lower right quadrant of a circle, concentricwith the shaft 5|. It will be clear that the angular position of thedispensing tube 49 determines the head of liquid above the tip 52, andhence if temperature and composition be constant, the rate of fiow fromthe tip, so that for each angular position of the dispensing tube, thereis a corresponding volume flow of acid.

It is desirable to maintain the acid solution at a nearly constanttemperature of plus or minus 1 to 2 degrees C. This may be done byimmersing cooling coils 54 in the constant level tank 46,

and by circulating cooling water through a jacket 56 surrounding thedispensing tube, and connected by flexible conduits 5'|.with thenecessary facilities.

For the titration of first carbonation filtrate, it is preferred to havethe distance between the center of the pivot shaft 5| and the capillarytip 52 about 20". The speed of rotary movement of the pivot shaft is ofcourse quite slow; and may be arranged at about .015 R. P. M. by the doceses use of suitable reduction gearing .58 driven by the reversiblesynchronous electric motor 9-. The alkaline first carbonation filtrateis .con-

ven'iently added to the acid at the lower end of the acid trough, theadjustably fixeddischarge tube 34 being positioned immediately above theend of. the trough, so that filtrate and acid. pass together through thedischarge nipple .61 into the. mixing tube .52, in which mixing. isinsured by allowing. the. acid and alkalito flow over about adozen smallglass beads .63, which may conveniently be about .12. in diameter.

The. mixture of: acid andalkali is nextpas'sed by or through a detectingelement which determines whether equivalent amountsofi acid and alkaliarepresent. Any oiia number ofdiiie'rent galvanic cells may begused.tomeasure .the hydrogen ion activity in .the solution. Examples ofthese cells are the .antimonyecalomel cells and the. glasselectrode-,calomel cells. Inasmuch as the hydrogen ion activity(expressed as pH, the log of the reciprocal of hydrogen ion activity) isthe most direct and exact measure of the degree of neutralization, it ispreferred to. usea galvanic cell composed of a glass electrode and a.saturated calomel electrode as the detecting element.

This detecting element is conveniently placed in a pH pct 64 having theshape shown in the drawing. This is madegof metal to protect theelectrodes from mechanical and electrical disturbances. The electrodesare placed in side arms t6 and 6] so that the tips of the electrodesproject into the stre m of liquid flowing through the pH pot. Thedischarge tube 6.8 of the pH pot is so arranged that the level of thesolution is maintained about /a" above the upper. or glass electrodebulb; and the internal diameter of the pH pot should be about /2 so asto keep the volume of solution in the pot at a minimum value.

There should be the least possible distance between the bottom of thetrough 53 and the glass electrode in side arm 56. Therefore nipple BIand tube .62 should be of minimum length and the glass electrode shouldalways be placed inthe uppermost side arm of the pH pot. .Within 5seconds after a change in'the flow of acid there should be an indicatedchange in the pH of the mixture in pH pct 64.

Means are providedfor measuring the F. produced in the cell, and forutilizing this'currenf to control motor means responsive to itsvariations, to swing thedispensing tube to vary the volume of aciddropping into the trough.

The electrodes of the cell are connected by leads ii and 12 .to anautomatic pH indicator 'lfi such as Beckmans model B. This instrumentmeasures the electric: potential produced by the electrodes; and itsscale 14 is calibrated in pH values corresponding to such potential, sothat the pointer at all times indicates the pH condition in the. pot.The instrument is provided with terminalsby which an additionalindicating meter at aremotepointmay be'connected; and I make use of.these terminals to connect, by

means of leads if? and'lil, a highly sensitive'moving coil relay it:This relay makes contact on one side when the current flowing throughthe coil is reduced and on the other side when the current is increased.Inasmuch as the magnitude of the current depends on the pH of themixture of the acid and alkali, it is evident that the operation ofthe'sensitive movingcoil relay depends on thispH value.

The relay .l s in turn controls-two relays .8 i and 3| functionswhenrelay 79' makescontact on the low side-19A and relay 32 functionswhen .relay 19 makes contact, on the high side 19B. Neither relay 8! nor.82 will function when the moving contact of relay i9 is in itsintermediate position.

Connected by the leads B5 to the power line 86 for control by the relays8| and 82 is the reversible synchronous electric motor 5! Limit switchesof conventional design, not shown, are provided to control the rotationof. the motor, to keepmovement of the dispensing tube .49 within itspermissible range in the quadrant selected for its operation.

The operation of the apparatus as so far. .de-

scribed is as follows: It is assumed that first carbonation juice isflowing through the filter pot 3; that, pressure andvacuum arealternately being supplied to the filter 6; that cooling. water is beingsupplied to the heat exchanger 2?; and that the static head on theorifice of the discharge tube 34 is adjusted so that the desired flow offirst carbonation filtrate is being obtained. Furthermore, it; isassumed that the potentiometer 13 is so adjusted that the moving contactof relay 79 is in its intermediate position when the. pH of theacid-alkali mixture'fiowing through the pH pot 54 has that valuecorresponding to the presence of chemically equivalent amounts of acidand alkali. For first carbonation filtrate and 0.0357 normal sulfuricacid, it has'been found that this pH value is 7.08 at 25 C. Thisadjustment of the electronic potentiometer is readily made.

Under these conditions, a stream of cooled first carbonation filtratewill be delivered from the discharge tube 34, at a constant rate andmixed with the acid solution flowing from the restricted orifice orcapillary tip 52. If chemically equivalent amounts of alkali and acidare present in the two streams, the mixture will be chemically neutraland have a pH value or" 7.08. The moving contact of the sensitive relay'll-lwill hence lie in its intermediate position and neither relay 8|nor relay 8? will operate, so that the shaft 5i is at rest. If, however,the mixture ofacid an alkali contains an excess of alkali, the: pH ofthe mixture will be greater than 7.08 and the moving contact of therelay 19 will make contact on the side 18B; and this in turn willcauserelay 82 to close. In turn,.the reversible motor will operate so as torotate the shaft iii in a clockwise direction. This will increase thestatic head of the acid column on orifice 52, and hence the flow of theacid solution will increase. When the rate of flow of the acid is suchthat the mixture of acid and alkali is chemically neutral or the pH isreduced to 7.08, the moving contact of relay 79' will seek theintermediate position, relay 82 will become inoperative and motor 59will stop. The dispensing tube 49 then remains at rest; and the rate offlow of the acid solution is constant;

Suppose now that the alkalinity of the'iirstmakes contact on the side19A. This causes relay 8 lt'o function and the motor operates'to rotateshaft- 5l in a counter-clockwise direction. The.

static head of the acid column on orifice 52 1s lessened andconsequently the now or acid is reduced. Equilibrium between the acidand alkali is thus again attained, the pH of the mixture equals 7.08 andthe dispensing tube 49 again comes to rest. Thus the flow of acid issubject to constant and automatic variation so as to maintain thechemical balance between acid and alkali,

From the above description it will be obvious that my continuoustitration apparatus i not necessarily restricted to the use of aconstant flow of alkali and a variable flow of acid. The acid flow couldbe made constant and the alkali flow varied. Similarly, it an acidsolution of unknown composition were being analyzed, this solution couldbe run through the apparatus at a constant rate while varying the flowof a solution of alkali of known strength or the alkali solution couldbe used at a constant rate of flow, while the rate of flow of the acidsolution was varied. In general, if VA and NA are the volume inmilliliters per minute and the concentration in equivalents per literfor the acid and VB and NB are the corresponding quantities for thealkali, the condition for equilibrium is that VANA=VBNB. It can bereadily seen that if any two of these quantitles are fixed in value, thevalues of the other two quantities bear a direct relationship to oneanother. Thus if VB and NA are fixed in value, NB bears a directrelationship to VA. This is the case in which the rate of flow of thealkali and the strength of the acid are held constant. Then the strengthof the alkali is directly proportional to the flow of acid. We mightalso hold VA and NA constant, in which case NB is inversely proportionalto VB.

We will assume that the automatic titrimeter is being used as firstdescribed, namely with a constant flow of alkali and a variable flow ofacid, the alkali being of varying strength and the acid of constantstrength. The flow rate of the acid is then a measure of the strength ofthe alkali.

Means are provided for measuring and recording the flow rate of acid.Such means include a recording potentiometer 9!, a 50-ohm resistance 92,a variable 50-ohm resistance 93, a variable 150-ohm resistance 94, and a1.5 volt battery 95,

in a circuit as shown in the upper part of the figure. A contact arm 96,fixed for movement with the shaft and dispensing tube 49, ranges overthe resistance 93; and a single pole double throw switch 9! permitsconnection of the potentiometer 9! across the resistance 92 throughleads 98 and 99 or across resistance 92 plus that portion of resistance93 included in the circuit by the contact arm 96. The battery 95supplies the current and the variable resistance 94 permits adjustmentof the current to a value of .007 ampere.

This adjustment is made by throwing switch 91 to the left so that thepotential drop between points A and B is measured. Inasmuch as the valueof resistance 92 is 50 ohms, the value of resistance 94 may be adjustedso that the observed potential drop is 0.350 volt. When switch 91 isthrown to the right, the potential drop between points A and C ismeasured.

It is now obvious that for every position of the output shaft 5| therewill be a corresponding flow of acid from orifice 52, and a correspnding position of the contact arm (position 0) on resistance 93. Thepotential drop across AC is therefore a direct measure of the flow ofacid and in turn this is a measure of the alkalinity of the firstcarbonation Juice. It is thus possible to calibrate the recordingpotentiometer directly in terms of alkalinity, simply by measuring theflow of acid for several different positions of the acid delivery tube49. Knowing the strength of the acid and the flow of the firstcarbonation juice, the alkalinity of the juice is easily calculated.

The values .007 ampere and .35 volt referred to above are not limitingor generally definitive, but merely those actually used in an apparatusembodying my invention, and on which the potentiometer 9| measured aminimum potential drop of .35 volt. With another potentiometer,different values might be necessary for correct operation.

I claim:

1. In titration apparatus, a movable liquid dispensing means movable tovary the static head and thus the amount of liquid dischargingtherefrom, means including a constant level device for maintaining acontinuous supply of the liquid to said dispensing means, a reactionchamber for receiving said liquid, means for introducing in constantvolume flow a second liquid into said chamber, a pair of electrodesarranged in the chamber to form with the liquid therein a galvanic cell,and means including means responsive to variation in the output currentof said cell for moving said dispensing means.

2. In titration apparatus, a chamber for holding liquid, movable meansfor introducing liquid in a variable volume flow into said chamber,means for introducing in constant volume flow a second liquid into saidchamber, a pair of electrodes arranged in the chamber to form with theliquid therein a galvanic cell, means including means controlled by theoutput current of said cell for controlling said movable means tocontrol the volume of liquid introduced thereby into said chamber, anelectric circuit, a recording potentiometer in said circuit, a variableresistance in said circuit with said potentiometer, and means connectedto and actuated by said movable means for controlling said variableresistance and thus the current flow in said circuit to saidpotentiometer.

3. In a titration apparatus, a movable liquid dispensing means movableto vary the static head and thus the amount of liquid dischargingtherefrom, said dispensing means having a restricted outlet meansincluding a constant level device for maintaining a continuous supply ofthe liquid to said dispensing means, a reaction chamber for receivingsaid liquid, means for introducing in constant volume flow a secondliquid into said chamber, a pair of electrodes arranged in the chamberto form with the liquid therein a galvanic cell, a motor operativelyconnected to the dispensing means to move the same, means includingrelay-controlled circuits for controlling the motor, and meansresponsive to the output current of said cell for selectively operatingsaid relays.

4. In a titration apparatus, a movable liquid dispensing means movableto vary the static head and thus the amount of liquid dischargingtherefrom, means for maintaining a continuous supply of the liquid tosaid dispensing means, a reaction chamber for receiving said liquid,means for introducing in constant volume flow a second liquid into saidchamber, a pair of electrodes arranged in the chamber to form with theliquid therein a galvanic cell, means including means responsive tovariation in the output current of said cell for moving said dispensingmeans, a recording potentiometer, a resistance in circuit therewith, andmeans connected for movement with the liquid dispensing means forvarying the resistance. i

5. In a titration apparatus, a pivotally mounted shaft, a movabledispensing tube fixed radially on said shaft for movement therewith tovarious angular positions, means connected to said tube for supplying aliquid thereto and positioned to give a constant head at the point ofsaid connection, the angular position of said tube regulating the statichead of said liquid and thus the rate of flow of said liquid throughsaid tube, a chamber for holding liquid, means for conducting liquiddischarging from-the dispensing tube at angularly adjusted positions tothe chamber, means for introducingv into said chamber a constant volumeflow of a second liquid, a pair of electrodes arranged in the chamber toform with the liquid therein agalvanic cell, a revensible-motor drivablyconnected to said shaft, normally' open circuits for supplyingelectrical energy to said motor, means selectively responsive to theoutput current of said cell for closing one of said circuits to energizethe motor to turn the shaft to vary the angular position of said tube,and means for measuring the rate of flow of the liquid passing throughsaid dispensing tube.

6. In a titration apparatus, a pivotally mounted shaft, a movabledispensing tube fixed radially on said shaft for movement therewith tovarious angular positions, means connected to said tube for supplying aliquid thereto and positioned to give a constant head at the point ofsaid connection, the angular position of said tube regulating the statichead of said liquid and thus the rate of flow of said liquid throughsaid tube, a chamber for holding liquid, means for conducting liquiddischarging from the dispensing tube at angularly adjusted positions tothe chamber, means for introducing into said chamber a constant volumeflow of a second liquid, a pair of electrodes arranged in the chamber toform with the liquid therein a galvanic cell, a reversible motordrivably connected to said shaft, normally open circuits for supplyingelectrical energy to said motor, a prime relay for closing each of saidcircuits, relay means for operating each of said prime relays, meansresponsive to the output current of said cell for selectively operatingthe relay means to operate one of the prime relays to close a circuit toenergize the motor to turn the shaft to vary the angular position ofsaid tube, and means for measuring the rate of .flow of the liquidpassing through said dispensing tube.

'7. In a, titration apparatus, a movable liquid dispensing means movableto vary the static head and thus the amount of liquid dischargingtherefrom, said dispensing means having a restricted outlet, means formaintaining a supply of the liquid to said dispensing means, a reactionchamber for receiving said liquid, means for introducing in constantvolume flow a second liquid into said chamber, a pair of electrodesarranged in the chamber to form with the liquid therein a galvanic cell,means including means responsive to variation in the output current ofsaid cell for moving said dispensing means, and means for measuring therate of flow of the liquid discharging from said dispensing means.

8. In a titration apparatus, a movable liquid dispensing means movableto vary the static head and thus the amount of liquid dischargingtherefrom, means including a constant level device for supplying theliquid to said dispensing means, a reaction chamber for receiving saidliquid, means for introducing in constant volume flow a second liquidinto said chamber, means including means associated with said chamberand responsive to changes in the'physico-chemical properties of thesolution created by the-mixture of said first and second liquids. formoving said dispensing means, and means for measuring the rate of fiowof the liquid dischargingfrom said dispensing means.

9. In a titration apparatus, a pivotally mounted shaft, means forturning said'shaft, a movable dispensing tube fixed radially onsaidshaft for movement therewith to variousangular positions, meansconnected to said tube for supplying a liquid thereto and positioned togive a constant head at the point of' said connection, the angularposition of said tube regulating :the static head of said liquid andthus the rate of flow of said liquid through said tube, a chamber forholding liquid, means for conducting liquid dischargingfrom thedispensing tube at angue larly adjusted positions to the chamber, meansfor introducing into said chamber, a constant volumefiowof a secondliquid, a pair of electrodes arranged in the chamber to form with theliquid therein a galvanic cell, and means responsible to the outputcurrent of said cell for actuating said means for turning said shaft tovary the angular position of said tube.

10. In a titration apparatus, a pivotally mounted shaft, a movabledispensing tube fixed radially on said shaft for movement therewith tovarious angular positions, means connected to said tube for supplying aliquid thereto and positioned to give a constant head at the point ofsaid connection, the angular position of said tube regulating the statichead of said liquid and thus the rate of flow of said liquid throughsaid tube, a chamber for holding liquid, means for conducting liquiddischarging from the dispensing tube at angularly adjusted positions tothe chamber, means for introducing into said chamber a constant volumeflow of a second liquid, a pair of electrodes arranged in the chamber toform with the liquid therein a galvanic cell, a reversible motordrivably connected to said shaft, normally open circuits for supplyingelectrical energy to said motor, and means selectively responsive to theoutput current of said cell for closing one of said circuits to energizethe motor to turn the shaft to vary the angular position of said tube.

11. In a titration apparatus, a pivotally mounted shaft, a movabledispensing tube fixed radially on said shaft for movement therewith tovarious angular positions, means connected to said tube for supplying aliquid thereto and positioned to give a constant head at the point ofsaid connec tion, the angular position of said tube regulating thestatic head of said liquid and thus the rate of flow of said liquidthrough said tube, a chamber for holding liquid, means for conductingliquid discharging from the dispensing tube at angularly adjustedpositions to the chamber, means for introducing into said chamber aconstant volume flow of a second liquid, a pair of electrodes arrangedin the chamber to form with the liquid therein a galvanic cell, areversible motor drivably connected to said shaft, normally opencircuits for supplying electrical energy to said motor, a prime relayfor closing each of said circuits, relay means for operating each ofsaid prime relays, and means responsive to the output current of saidcell for selectively operating the relay means to operate one of theprime relays to close a circuit to energize the motor to turn the shaftto vary the angular position of said tube.

12. In a titrating apparatus, a pivotally mounted shaft, means forturning said shaft, a movable dispensing tube fixed radially in saidshaft for movement therewith to various angular positions, a constantlevel reservoir for holding a liquid, a conduit for connecting thereservoir to the dispensing tube at a point removed from its free end,the angular position of said tube regulating the static head of saidliquid and thus the rate of flow of said liquid through said tube, achamber for holding liquid, means for conducting liquid discharging fromthe dispensing tube at various angular positions to the chamber, meansfor introducing in constant volume flow a second liquid into saidchamber, a pair of electrodes arranged in the chamber to form with theliquid therein a galvanic cell, means controlled by the output currentof said cell for actuating said means for turning said shaft to vary theangular position of said dispensing tube, and means for measuring therate of fiow of the liquid passing through said dispensing tube.

ERWIN E. MORSE.

REFERENCES CITED The following references are of record in the file ofthis patent:

12 UNITED STATES PATENTS Number Name Date 1,089,030 Angeli Mar. 3, 19141,340,649 Crandon May 18, 1920 1,341,790 Edelman June 1, 1920 1,450,023Edelman Mar. 2'7, 1923 1,530,833 Keeler Mar. 24, 1925 1,643,243 HatfieldSept. 20, 1927 1,759,996 Parker May 27, 1930 1,830,333 Parker Nov. 3,1931 1,860,321 Ramsey et a1 May 24, 1932 1,951,035 Parker Mar. 13, 19341,956,741 Hornberger May 1, 1934 2,044,164 Gullicksen June 16, 19362,308,917 Hardinge Jan. 19, 1943 2,367,949 Langer Jan. 23, 1945 OTHERREFERENCES Hickman et al., Automatic Titrating Devices, Ind. and Eng.Chem, Anal. ed., vol. 5, No. 1, J anuary 15, 1933, pages 65-68.

1. IN TITRATION APPARATUS, A MOVABLE LIQUID DISPENSING MEANS MOVABLE TOVARY THE STATIC HEAD AND THUS THE AMOUNT OF LIQUID DISCHARGINGTHEREFROM, MEANS INCLUDING A CONSTANT LEVEL DEVICE FOR MAINTAINING ACONTINUOUS SUPPLY OF THE LIQUID TO SAID DISPENSING MEANS, A REACTIONCHAMBER FOR RECEIVING SAID LIQUID, MEANS FOR INTRODUCING IN CONSTANTVOLUME FLOW A SECOND LIQUID INTO SAID ABOUT 20 DAYS TO ABOUT 30 DAYS SOTHAT SAID SOLUCHAMBER TO FORM WITH THE LIQUID THEREIN A GALVANIC CELL,AND MEANS INCLUDING MEANS RESPONSIVE TO VARATION IN THE OUTPUT CURRENTOF SAID CELL FOR MOVING SAID DISPENSING MEANS.